Effect Of Total Glucosides Of Paeony On Activation Of JAK/STAT Pathway In The Kidney From Diabetic Rats

Background and objective Diabetic nephropathy is the main cause of end-stage renal disease requiring dialysis. A basic mechanism underlying diabetic nephropathy appears to be the high glucose (HG)-induced overexpression of transforming growth factorβ1 (TGFβ1) and the accumulation of extracellular matrix (ECM) molecules, such as collagen IV and fibronectin. Recent studies suggest that Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling cascades may contribute to diabetic nephropathy. This pathway is mainly related to renal cell growth, production of the cytokine TGFβ1, as well as the ECM proteins collagen IV and fibronectin. The recent study in vitro evidence have demonstrated that the inhibition of JAK/STAT signal transduction have significant protective effects on DN. Total glucosides of paeony (TGP) are active compounds extracted from the dried roots of Paeonia lactiflora Pall which has been used for gynaecological problems and for cramp, pain and giddiness for over 1500 years in Chinese medicine. The effects of TGP have been extensively proved for many years with an exact therapeutic effect on systemic lupus erythematosus, rheumatoid arthritis and hepatitis without evident toxic or side effects. The therapeutic effects involve to anti-inflammatory, analgesia, antioxidative, antihepatic injury and immunoregulatory activities. The purpose of the present study was to investigate the effect of TGP on activation of JAK/STAT signal transduction in the kidney from diabetic rats induced by STZ. Methods Fifty adult male Sprague-Dawley rats were separated into five groups at random. Control group (n=10), model group (n=10), model group treated with TGP (50 mg/kg/d, n=10), model group treated with TGP (100 mg/kg/d, n=10) and model group treated with (TGP 200 mg/kg/d, n=10). Diabetes was induced with STZ (60 mg/kg/d) in rats, and TGP was orally administered once a day for 8wk to rats by gavage. Eitht weeks after STZ injection, the following determinations were done in samples: 1.BG were determined according to standard methods; 2. Urinary albumin excretion rate was measured by enzyme immunoassay (EIA);3.Western-blotting for renal p-JAK2,p-STAT3 and 1α(IV)collagen protein were quantified densitometrically,and immunohistochemistry for TGFβ1 was performed by streptavidin-biotin complex(SABC) technique. Results 1.There were a significant increased in BG (p<0.01) and significantly increased in Body Weight (BW) (p<0.01) in diabetic rats compared with control group after 8 weeks'induction of STZ. The BG level of TGP-treated goup (50,100与200 mg/kg/d) have no statistically significant. Kidney weight(KW) to BW(KW/BW) in TGP (50,100 and 200 mg/kg/d) were decreased compared with model group,but there were no statistically significant. Elevated 24h urinary albumin excretion rate in the model group were markedly attenuated by TGP treatment with 50,100 and 200 mg/kg/d.2. Western blot analysis noted that the expression of p-JAK2,p-STAT3 were significantly increased in diabetic rats with respect to control group rats, while TGP (50,100 and 200 mg/kg/d) could reduce the expression of p-JAK by approximately 22.3%,50.5% and 43.2%,and TGP (50,100 and 200 mg/kg/d) could reduce the expression of p-STAT3 by approximately 20.9%,61.1%与42.3%. 3. Densitometric analysis of western blot analysis noted a 2.7 fold increase in the amount of 1α(IV) collagen protein from model group rats with respect to control group rats; TGP (50,100 and 200 mg/kg/d) could reduced 1α(IV) collagen protein by approximately 47.9%,60.4% and 72.9%. There was minimal immunohistochemistrical staining for TGFβ1 in glomeruli and tubulointerstitium in control group.Immunostaining for TGFβ1 was markedly increased in model group in glomeruli and tubulointerstitium, TGP (50,100 and 200 mg/kg/d) could significantly reduce the expression of TGFβ1.Conclusion Our data suggest that TGP treatment ameliorates early renal injury via the inhibition of activation of JAK/STAT signal transduction and the relevant TGF-β1- collagen IV expression in the kidney from diabetic rat.